a) Field of the Invention
The present invention relates generally to actively vibration reducing control apparatus and method applicable to a vehicular engine mount on which a vehicular engine as a vibration source is mounted.
The present invention particularly relates to adaptive control apparatus and method for actively reducing the vibration transmitted from the vehicular engine in which a control vibration developed from a control vibration source is interfered against a vibration transmitted from the engine to a vehicle body to reduce the transmission of the vibration and a load of an identification operation for a transfer function between the control vibration source and a residual vibration detector included in a control algorithm to drive the control vibration source is reduced and an improvement in an accuracy of the identification on the transfer function is achieved.
b) Description of the Related Art
In a case of various previously proposed active vibration reducing control apparatuses, transfer functions, each transfer function being established between a control vibration source and a residual vibration detector, are mutually different from each other according to characteristic deviations for respective apparatuses to which the previously proposed active vibration reducing control apparatus are applied and for respective installations on which the previously proposed actively vibration reducing apparatuses are installed.
In addition, there is a possibility that each of the transfer functions is varied from its originally established state due to its characteristic variation along with a use of the apparatus to which each of the previously proposed active vibration reducing apparatus is applied.
Hence, in order to execute a highly accurate vibration reducing control, it is desirable to identify the transfer function after each one of the previously proposed actively vibration reducing control apparatuses is incorporated into the apparatus to which each one thereof is applied or it is desirable to identify the transfer function whenever a regular check for the apparatus to which each one thereof is applied.
A Japanese Patent Application First Publication No Heisei 6-332471 published on Dec. 2, 1994 exemplifies a technique for identifying the transfer function described above.
In the above-identified Japanese Patent Application First Publication, an identification sound or an identification vibration is caused to be developed according to an impulse signal from a control source or a control vibration source and its response is measured by means of a residual noise detector or a residual vibration detector.
Consequently, the identification of the transfer function required in the control algorithm of an active noise controller or an active vibration controller can be achieved.
A time at which the identification sound or the identification vibration is developed according to the impulse signal is limited to a time immediately before the time transferred from a state in which a noise or the vibration from a noise source or a vibration source is not developed to a state in which the noise or the vibration is developed. Hence, the identification of the transfer function can be made without introduction of a remarkable increase in a calculation load on the controller and without an unpleasant feeling given to a human kind.
Furthermore, a Japanese Patent Application First Publication No. Heisei 3-259722 published on Nov. 19, 1991 exemplifies another technique of the identification of the transfer function.
In the latter Japanese Patent Application First Publication, a noise reducing apparatus in which a noise developed by a compressor installed in a refrigerator and radiated externally through a mechanical room duct is cancelled before the noise is to be radiated externally through the duct, a loud speaker and a microphone are installed to perform a noise reduction control within the duct, the control noise is developed from the loud speaker according to the drive state of the compressor to reduce the noise, and the identification sound is developed from the loud speaker according to a white noise whenever the compressor is halted in order to prevent a noise control characteristic from being deteriorated, and the transfer function between the loud speaker and the microphone is measured to identify a transfer function filter.